Ultra high frequency apparatus



June 10, 1947. w. HAI-:SELER ET AL 2,421,784

ULTRA-HIGH FREQUENCY APPARATUS Filed Feb. 24, 1945 v gw Snventorg Bg .W501i A l Gttorrieg Patented June 10, 1947 ULTRA HIGH FREQUENCY APPARATUS Leonard W. Hacseler, Merchantvillaand Samuel H. Watson, Audubon, N. J.,V assign`ors to Radio Corporation of America, a corporation of Dela- Wavre Application February 24, 1943, serial No. 476,994

9 Claims.

lThis invention relates generally to ultra-high frequency apparatus and more particularly to an improved circuit and apparatus for ultra-high frequency genere-ting and amplifying systems.

Briey, the invention comprises a tuned concentric ultra-high frequency coupling device whereby a substantially constant L/C ratio may be obtained over a relatively wide operating frequency range. It is customary to provide concentric line tuning devices for use with ultrahigh frequency thermionic tubes. However, the tuning of such circuits introduces relatively serious practical diiculties since variable capacitors customarily used for this purpose also introduce objectionable inductive and resistive components. The instant invention is illustrated in combination with a conventional light house ultra-high frequency thermionic tube. The coupling circuits comprise three concentric cylinders coupled respectively to the cathode,` the control electrode and the anode of the thermionic tube. Preferably, the length of the cylinders should be of the order of an odd multiple of a quarter wave length at the operating frequency. This length may be adjusted by providing a telescoping short-circuited section at the end of the cylinders removed from the thermionic tube. Input and output circuits may be coupled through conventional coaxial transmission lines, or any other conventional means, to suitable points on the concentric cylindrical conductors which comprise the thermionic tube circuits. Tuning of the anode circuit, for example, may be accomplished by providing a capacitive member movable along one of the concentric cylinders to provide capacitive coupling between said cylindrical member and another one of the concentric cylindrical conductors. By moving this capacitive element axially between the concentric cylindrical conductors, a substantially constant capacitive coupling may be maintained at any desired point in the circuit. The position of the lumped capacitive element may be adjusted by suitable means extending outside of the short circuiting conductive end structure remote from the thermionic tube.

Among the objects of the invention are to provide a new and improved method of and means for generating ultra-high frequency oscillations. Another object is to provide an improved method of and means for amplifying ultra-high frequency signals. A further object is to provide an improved method of and means for coupling quency thermionic tube. Still another object is electric, to the anode 3.

to provide improved ultra-high frequency thermionic tube circuitrcomponents( which comprise a plurality of concentric cylindrical conducting electrodes including means Vfor varying the elec-l trical characteristics of the various resultant component circuits. A further object o f the invention is to provide a Aconcentric cylindrical tuning element for use Ving ultra-high frequency circuits whereby a substantially constant L/ C ratio is obtained over a relatively wide frequency tuning range, u v

The invention Will beidescribed ,in greater detail by reference to the accompanyfig drawing of which Figure 1y is a crossfsectional elevational` view of a preferred embodimentthereof; lFigure 2 is a cross-sectional fragmentary Viewl of a Inodification of the embodiment illustrated in Figure l; and Figure 3 isa schematiccircuit (lagram of the equivalent electrical circuit `of` the devices illustrated in Figures, 1 and 2. Similar reference numeralsare applied to similar elements throughout the drawing. Y, M

Referring to Figure A1, an ultra-high frequency thermionic tube of the` flight house/type such as, for example, the RCAl type Gril-44,6,l includes a cathode l, a control electrode 2 and annanode 3. The operating potentials for `the cathode and control electrode may be provided in Vany coni/enfl tional manner, not shown. V Three concentrically disposed cylindrical conductive elements4.V 5v and 6 comprise coaxial tuning. elements which form the thermionic tube coupling circuits. One end of the first conductive `element 4 isconnected to the cathode I. One endA of the second conductive element 5 is connected to the control eleotrode 2v and the corresponding end of' the third conductive element n(i is connected.v through a small capacitor l, having amica or other suitable diy The rem'air'ling ends of the concentric conductors 4, `5 and 6 are vtelescoped with similar conductive elements i4, i5 and I6 which terminate in a shortci'rcuiting plate IT, which may be' considered to' be at ground potential. The telescoping sections of the concentric coupling device are adusted toA provide a. length of the order of an o dd multiple of one quarterv wave length at the operating frequency. A snorting plug 20, which may be operated externally by an adjusting knob 2|, may be pro'- vided` for `adjusting the length of the inner line 6 independently of theintermediate and outer lines 5` and 4', respectively, in order to compensate for differences in tubev inter-electrode capacitances. Y

A fourth cylindrical' conducting element 8,

which includes a spring member `E), surrounds a portion of the third conducting elements 6, and is in electrical contact therewith. The outer face I of the fourth conducting element 8 provides capacitive coupling with the inside surface of the second concentric conducting element 5. The resulting capacitive coupling provides a lumped capacity between the corresponding circuit elements. rFhis lumped capacity may be provided at any desired point in the coupled circuits by moving the fourth conductive element 8 axially between the conductive elements and 6 by means of tuning rods II and I2 which extend outside of the conductive plate I'l at a point remote from the thermionic tube. Preferably, the tuning rods II and I2 are connected together by a suitable conductive member I3 to provide a conventional adjusting member. Anode potential may be supplied by a lead through the interior of the inner conductive element 6 in any conventional manner. Preferably this circuit should include an isolating impedance device such as a reactance coil I8 and/or a resistor I 9.

If the circuit is to be used as an amplier, input signal potentials may be applied to predetermined points on the two outer cylindrical conductive elements 4 and 5 to provide suitable impedance matching to the driver circuit. Output potentials may be derived from suitable points on the intermediate and inner concentric conductive elements 5 and 6, respectively, to provide suitable output impedance matching.

If the circuit is to be adapted to the generation of the ultra-high frequency oscillations, the input connections may be omitted and the circuit components varied to provide suitable reaction therefor.

Figure 2 is a fragmentary cross-sectional View of the device described in Figure 1 wherein the adjustable capacitive element comprises a cylindrical insulating member 22 having a relatively high dielectric constant, such as, for eX- ample, polystyrene. The position of the capacitive element may be adjusted axially between the conductive elements 5 and 6 as described heretofore. This modication provides the advantage of absence of sliding contacts which would introduce noise in receiver circiuts.

Figure 3 represents the equivalent electrical circuit for the amplifying device described in Figure 1. It should be noted that the eiect of adjusting the position of the capacitive element 8 is eiectively to couple a xed capacitor to predetermined points in an inductive circuit coupling the anode and control electrodes of the thermionic tubes. The effect of varying the position of the input terminals on the two outer concentric conductors 4 and 5 is to couple the input circuit to predetermined portions of the inductive circuit connecting the cathode I With the control electrode 2 of the thermionic tube.

It should be understood that the capacitive element 8 may be similarly adapted to tune other desired thermionic tube circuits and that a plurality of such capacitive elements may be provided for simultaneous adjustment of the operating characteristics of a plurality of such circuits.

Thus the invention described comprises a novel tuning device for the purpose of coupling ultrahigh frequency thermionic tube electrodes for generating or amplifying ultra-high frequency currents.

We claim as our invention:

1. An ultra-high frequency circuit which includes a thermionic tube having at least a cathode electrode, a control electrode and an anode electrode, a plurality of concentric cylindrical conductive elements, means connecting one end of a first of said elements to one of said tube electrodes, means connecting one end of a second of said elements to another of said tube electrodes, conductive means connecting together the remaining ends of said elements, a movable capacitive element in operative relation to said rst and second conductive elements, means for adjusting the position of said capacitive element with respect to said conductive elements for tuning said circuit, means connecting one end of a third of said conductive elements to a third of said tube electrodes, and means connecting the remaining end of said third conductive element to said remaining ends of said rst and said second conductive elements.

2. An ultra-high frequency circuit which includes a thermionic tube having at least a cathode electrode, a control electrode and an anode electrode, a plurality of concentric cylindrical conductive elements, means connecting one end of a iirst of said elements to one of said tube electrodes, means connecting one end of a second of said elements to another of said tube electrodes, conductive means connecting together the remaining ends of said elements, a movable capacitive element in operative relation to said first and second conductive elements, means for adjusting the position of said capacitive element axially with respect to said conductive elements for tuning said circuit, means connecting one end of a third of said conductive elements to a third of said tube electrodes, and means connecting the remaining end of said third conductive element to said remaining ends of said first and said second conductive elements.

3. An ultra-high frequency circuit which includes a thermionic tube having at least a cathode electrode, a control electrode and an anode electrode, a plurality of concentric cylindrical conductive elements, means connecting one end of a rst of said elements to said control electrode, means connecting one end of a second of Said elements to said anode, conductive means connecting together the remaining ends of said elements, a movable capacitive element in operative relation to said rst and second conductive elements, and means for adjusting the position of said'capacitive element with respect to said conductive elements for tuning said circuit.

4. An ultra-high frequency circuit which includes a thermionic tube having at least a cathode electrodey a control electrode and an anode electrode, a plurality of concentric cylindrical conductive elements of the order of a predetermined odd multiple of a quarter wave in length, means connecting one end of a rst of said elements to one of said tube electrodes, means connecting one end of a second of said elements to another of said tube electrodes, conductive means connecting together the remaining ends of said elements, a movable capacitive element in operative relation to said first and second conductive elements, means for adjusting the position of said capacitive element with respect t0 said conductive elements for tuning said circuit, means connecting one end of a third of said conductive elements to a third of said tube electrodes, and means connecting the remaining end of said third conductive element to said re-` maining ends of said rst and said second conductive elements.

5. Apparatus of the type described in claim 4 including a source of input signals, and means for coupling said source to predetermined points on a predetermined pair of said conductive elements.

6. An ultra-high frequency circuit which includes a thermionic tube having at least a cathode electrode, a control electrode and an anode electrode, a plurality of concentric cylindrical conductive elements, means connecting one end of a rst of said elements to one of said tube electrodes, means connecting one end of a second of said elements to another of said tube electrodes, conductive means axially movable along said conductive elements connecting together the remaining ends of said elements, a movable capacitive element in operative relation to said rst and second conductive elements, means for adjusting the position of said capacitive element with respect to said conductive elements for tuning said circuit, means connecting one end of a third of said conductive elements to a third of said tube electrodes, and means connecting the remaining end of said third conductive elemeni-J to said remaining ends o-f said rst and said second conductive elements.

7. Apparatus of the type described in claim 1 including means movable axially along a second predetermined pair of said conductive elements for deriving energy therefrom.

8. Apparatus of the type described in claim 1 characterized by the fact that said capacitive element is a cylindrical insulating material having a relatively high dielectric constant.

9. An ultra-high frequency circuit which includes a thermionic tube having at least a cathode electrode, a control electrode and an anode electrode, a plurality of concentric cylindrical conductive elements, means connecting one end of a first of said elements to one of said tube electrodes, means connecting one end of a .Second of said elements to another of said tube electrodes, annular conductive means connecting together the remaining ends of said elements, a movable capacitive element in operative relation .to said rst and second conductive elements,

REFERENCES CITED The following references are of record in the ie of this patent:

UNITED STATES PATENTS Number Name Date 2,132,208 Dunmore Oct. 4, 1938 2,169,305 Tuniek Aug. 15, 1939 2,169,306 Tuniek Aug. 15, 1939 2,281,041 Labin Apr. 28, 1942 2,235,414 White Mar. 18, 1941 2,262,365 Kinn Nov. 11, 1941 2,302,798 Percival Nov. 24, 1942 

